There are two different methods for making panels which serve as background for the present invention, both of which result in a somewhat similar panel construction. The difference is that one method is capable of building into the panel more softness by including larger amounts of foamed material. Basically, this softer configuration is used in the more expensive luxury cars, whereas the other method is used basically in the large majority of other vehicles.
The method of making the luxury panel is essentially a two-stage process. In the first stage of the process, a substrate which is in the form of the panel is made by placing a fiberglass reinforcing mat in the lower half of a two-part mold and then filling the lower half of the mold with a foamable material such as liquid polyurethane capable of being cured into a foamed condition. After the foamable material has been inserted into the lower half of the mold, the upper half is moved down and then the foamable material is cured under heat to complete the substrate which is fairly rigid. In the second stage of the process, the substrate molded in the first stage is placed in the upper half of a second two-part mold. The lower part of the mold is in essence a vacuum mold. The second stage procedure is begun by moving a heated sheet of imperforate vinyl over the bottom part of the mold and then drawing by vacuum the heated sheet into the mold so that the three-dimensional configuration is formed on the vinyl. After the vinyl has been moved into engagement with the mold by the vacuum source, an amount of foamable material such as liquid polyurethane is then injected into the mold on top of the vinyl and thereafter the upper part of the mold which contains the substrate is then moved into cooperating relation with the lower part and the foamable material is cured into a relatively soft foamed condition.
The other more economical process is essentially a one-stage process which utilizes a two-part mold, the lower part of which again is a vacuum mold for the vinyl exterior sheet of the door panel to be made. In this case, the vinyl comes as the outer layer of a laminate which includes a layer of foamed material bonded thereto. The laminate is initially heated and then vacuum-drawn into the lower part of the mold. Next, a mat of fiberglass or similar reinforcing is placed inside the laminate vacuum adhered to the lower mold and, thereafter, a liquid polyurethane is added to the lower mold part over the vacuum-held laminate. The upper mold part is then closed and essentially a relatively rigid substrate is molded integrally with the vinyl laminate. In this process, it is not possible to provide much thickness and softness in the foam that is laminated with the vinyl or at least not as much as can be used in the second step of the two step process.
One area where the difference in softness is particularly noticeable is in the arm rest portion of the panel. There is a need in the more economical process to improve the softness of the arm rest portion in a cost effective manner.